Method of treating oil and gas wells



' water from these layers by suit agent capable of forming insoluble compounds 45 Patented June 11, 1940 UNITED STATES PATENT OFFICE 2,204,223 METHOD or rename 011. AND GAS WELLS Howard C. Lawton and Albert G. Loomis,

Berkeley, Calif" assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application January 30, 1939,

, Serial No. 253,604

Claims. (Cl. 166-21) This invention pertains to the treatment of oil alcohols such as methyl cellosolve, cellosolve, and gas wells and is more specifically concerned isopropyl cellosolve, the carbitols, etc.; esters with an improved method for soldifying unsuch as butyl lacetate, glycol diacetate, carbitol table formations and selectively sealing off water acetates, or cellosolve acetates. Pyridine and/or 5 and gas formations traversed by wells. mixtures of pyridine, nitrogen bases, and

It is well known that compounds which hy- Edeleanu extract from kerosene .with the above drolyze in the presence of water to form insolusolvents may likewise be used. For example, esble substances may be used to plug water-bearing pecially favorable results have been obtained strata traversed by oil wells. Compounds that with the following mixtures:

can be used for this purpose are, for example, Per cent n silicon tetrachloride, silicon esters, such as dea. Methyl propyl ketone 18 scribed in the co-pending application Serial No. Acetone 3'7 99,943, filed September 9, 1936, and anhydrous so- Nitrogen bases 45 lutions of metal alcoholates, such as described in the etc-pending application Serial No. 174,654, ggizii gg n l5 filed November 15, 1937, now Patent No. 2,169,458 Edeleanu ga 30 granted August 15, 1939.

It is also known that oil bearing strata which 0- et y t yl eiio 50 are often adjacent water bearing layers contain ethyl sobuty etO e 50 20 small amounts of connate water and in many wetting agents which may be added to Said 20 cases this amount of water is sufficient t treating liquids for the purpose of more effecdrolyze at least P the abpve compmmds tive water removal may be amines such as trion their introduction into these strata with the methylamine or triethanol amine esters Such as p q result i plugging action within the naphthalene sulphonic acid ester, oleic acid sulj formations phate, oleo glyceryl sulphate, sulphonated oils, 25

It therefore an cbJect. of thls mventlon to such as sulphonated castor oil, or alkyl sulphates provide a method for s.elect:wely Pluggingwatflsuch as those commercially known as the Garbearmg strata wherein on'bearmg Strata are dinols. The addition of approximately 1% of a first fr.eed of cpnnate a treatment the wetting agent will suifice for the purpose of this well with an oil-soluble liquid capable of dissolvinvention 3 mg removmg Sald water and f Briefly, the invention resides in introducing pearmg Strata then plugged by mimduclng into the formation traversed by a well an oil-solumto h {ormatlon compounds capable P ble treating solution capable of dissolving the wathere n insoluble substances by reaction with tel. causing Said treating Solution to dissolve j' the water in both the oil and the water layers, It is a further ob ect of this invention to prowithdrawing the treating Solution from the vide for the above treatment suitable oil-soluble formation and from the well allowing the water treatmg liquld? contaming wetting agents removed from the oil-bearing layer to become pable of reducmg surfacetensmn of Water replaced with oil from more remote reaches of 40 whereby a .more efiectwe rellmval connate the oil-bearing layer, allowing the water removed- 40 ter fliom Strata 1s P F from the water-bearing layer to become replaced It is another ob ect of this invention toprowith water from more remote reaches of the i a metihod for mcreasmg the permeability of water-bearing layer, and then introducing into oll'pmducmg layers throughthe removal of the well and forcing into the formation a sealing able trefmng q by reaction with water, whereby a sealing pre- The hquids i be used to carry P cipitate is caused to form only within the waterthe process of this invention are those in which bearing layer, thus ff tivel plugging said layer both 011 and Water a hlgmy Soluble for In a preferred embodiment, the treating liquid,

ample, ketones such as acetone methyl ethyl comprising a water and oil-miscible solvent, is 50 ketone, m hyl p yl ketone, hyl k one, introduced into the well and driven into both the alcohols such as n-prqpy alcohol. D DY oil and water strata by application of pressure cohol, n-butyl alcohol, secondary-butyl alcohol, achieved by any well known means such as an etc; ethers, particularly cyclic ethers such as overburden of oil or water, or gas or air pressure.

dioxane, tetramethylene oxide, furan, etc.; ether For example, the treating liquid may be methyl 55 therefore, normally cannot .be' withdrawn with the oil. By introducing a treating solution to dissolve the water and to lower the interfacial tension between water and oil and withdrawing the resulting liquid from the oil-bearing strata, the water is released from the capillary spaces and removed from the well with the treating liquid. These capillary spaces are then available for the flow of oil, and as itis known that the rate of production obtained in an oil well is highly dependent on the permeability of the formation in the immediate vicinity of the well, the clearing of the capillary spaces of bound water to permit a flow of oil through them, represents an increase in permeability and, hence, an increase in the rate of production. Of course, the treatment does not affect water-bearing strata as water withdrawn therefrom with the treating fluid is replaced by further flow of water from more remote portions of the water-bearing layer. Hence, after the treating solution has been forced into the formation and has dissolved, become associated with, or released the water in the oilbearing strata, the well is bailed out, if necessary, and "brought into production as the process of withdrawing liquids from a well is commonly called in oil-well drilling practice. The oil-bearing strata now being water-free, the desired water shut-off chemical, for example, ethyl silicate, is then forced into both the oil and water strata by means of pressure. The chemical reacts in water-bearing strata with the water to form a plugging material, but cannot react in oil formations because the water had been previously removed by the treating liquid. Water shut-off compounds which form insoluble substances upon reaction with salts normally presentin ground waters may also be applied to the present process, although compounds reacting with water are preferable due to the formation of a greater amount of precipitate.

It is apparentthat by the method herein described not only can a high degree of selectivity be obtained in plugging water strata, butthe permeability of the oil-producing layers can also be increased at the same time. The combination of these effects, that is, shutting off water on the one hand, and increasing the oil production on the other, is highly desirable in the art of economical and conservative oil production.

The examples shown herein are not intended to limit the scope, but rather to illustrate the broad aspects of this invention. It is to be understood that combinations of other solvents and other sealing agents than those given hereinabove may be equally effective and may be employed without departing from the spirit of the present invention.

We claim as our invention:

1. In the process of selectively sealing off a formation traversed by a well, said formation comprising water-bearing layers adjacent oilbearing layers holding relatively small quantities of connate water, the steps of introducing into the well and forcing into the formation an inert non-aqueous solvent miscible with water and oil,

allowing said solvent to dissolve the formation waters, withdrawing the solvent and the waters dissolved therein from the formation and the well, whereby the water removed with the solvent is caused to be replaced with water in the waterbearing layers and with oil in the oil-bearing layers, and introducing into the well and forcing into the formation a sealing agent forming oil and water insoluble compounds by hydrolysis, whereby a sealing precipitate is caused to form within the water-bearing layer.

2. In the process of selectively sealing off a formation traversed by a well, said formation comprising water-bearing layers adjacent oilbearing layers holding relatively small quantitiesof connate water, the steps of introducing into the well and forcing into the formation an inert non aqueous' solvent miscible with water and oil, said solvent containing a small amount of a surface-tension reducing agent, allowing said solvent to dissolve the formation waters. withdrawing the solvent and the waters dissolved therein from the formation and the well, whereby the water removed with the solvent is'caused to be replaced with water in. the water-bearing layers and with oil in the oil bearing layers, and introducing into the well, and forcing into the formation a sealing agent forming oil and water insoluble compounds by hydrolysis, whereby a sealing precipitate is caused to form within the water-bearing layer.

3. In the process of selectively sealing off a formation traversed by a well, said formation comprising water-bearing layers, adjacent oilbearing layers holding relatively small quantities of connate water, the steps of introducing into the well and forcing into the formation an inert non-aqueous solvent miscible with water and oil, said solvent containing a heterocyclic nitrogen base compound, allowing said solvent to dissolve the formation waters, withdrawing the solvent and the waters dissolved therein from the formation and the well, whereby the water removed with the solvent is caused to be replaced with water in the water-bearing layers and with oil in the oil-bearing layers, and introducing into of connate water, the steps of introducing into the well and forcing into the formation an inert non-aqueous solvent miscible with water and oil, said solvent containing nitrogen bases, allowing said solvent to dissolve the formation waters, withdrawing the solvent and the waters dissolved therein from the formation and the well, whereby the water removed with the solvent is caused to be replaced with water in the water-bearing layers and with oil in the oil-bearing layers, and introducing into the well and forcing into the formation a sealing agent forming oiland water insoluble compounds by reaction with water, whereby a sealing precipitate is caused to form within the water-bearing layer.

5. In the process of selectively sealing off a formation traversed by a well, said formation comprising water-bearing layers adjacent oilbearing layers holding relatively small quantities of connate water, the steps of introducing into the well and forcing into the formation an inert non-aqueous solvent miscible with water and oil, said solvent containing pyridine, allowing said solvent to dissolve the formation waters, withdrawing the solvent and the waters dissolved formation a sealing agent forming oil and water therein from the formation and the well, whereby insoluble compounds by reaction with water, the water removed with the solvent is caused to whereby a sealing precipitate is caused to form be replaced with water in the water-bearing within the water-bearing layer.

5 layers and with oil in the oil-bearing layers, and HOWARD C. LAWTON. fl

introducing into the well, and forcing into the ALBERT G. DOOMIS.

D l S C L A l M E R 2,204,223.-Ho'ward O. Lawton and Albert G. Loomls, Berkeley, Calif. ME THO1 0F TREATING OIL AND GAS WELLS. Patent dated June 11, 1940. Disclaimer filed February 4, 1941, by the assignee, Shell Development Company. Hereby enters this disclaimer to claim 1 in said specification.

[Qfliclal Gazette March 11, 1941.]

DISCLAIMER 2,204,223.Howard O. Lawton and Albert G. Loomis, Berkeley, Calif. METHOD OF TREATING OIL AND GAS WELLS. Patent dated June 11, 1940. Disclaimer filed February 4, 1941, by the assignee, Shell Development Company. Hereby enters this disclaimer to claim 1 in said specification.

[Oficial Gazette March 11, 1941.] 

